This:
With the front suspension of this:
Goal: to transport 2 people or 1 person + 100 kg of cargo, with the benefits of:
-not getting wet when it rains
-not falling on your head when you get bumped into by a car
-low taxation and low fuel consumption
-legally lane-splitting when its rush hour.
-3 wheels means I can drive it on my car license / don't need a motorcycle license.
-3 wheels means it doesn't fall over without extending 'landing gear'
-better fuel efficiency through streamlined body instead of upright toilet seat position.
Construction would probably be steel frame with lexan and fiberglass outter shell, though could also be carbon fiber monocoque if needed to save weight. There are some weight limitations on what is considered a motorcycle.
Drivetrain would either be motorcycle or electric, not particularly picky on that right now, motorcycle would probably be the cheaper and lighter option, plus easier to get it road legal.
Budget, I think somewhere between 12k and 15k including a used donor motorcycle for drivetrain and suspension should do the trick. I just don't have the money or the time.
Also, this isn't a novel idea, I got inspired by students from my university who attempted the exact same, but got stuck in the "getting a custom vehicle road legal" papermill and then gave up.